The difficulty encountered on current layer-by-layer powder sintering machines is their low capacities due to the alternating linear sweeping of the work area, which is a handicap because the back-and-forth movements take considerable time, which is detrimental for circular parts with a large diameter, and also because the cooling of the parts produced in the containers is very time-consuming.
The temperature of the deposited layers is practically not controlled or regulated continuously, which requires a certain time for cooling before it is possible to apply new layers, as well as afterwards to remove the finished parts from the container holding them.
The principle of construction by stacking layer by layer is natural and has been used since the beginning of time to construct buildings, even before the Egyptian pyramids.
It is now allowed to build products with very complex helical shapes with increasingly thin layers, which were never before possible to manufacture with the tools of the time, owing to cumulative technical progress made simultaneously in all fields:                the precision of mechanical construction,        resin polymerization, laser powder sintering, cutting thin sheets, and adding material,        the performance of the computer hardware added to that of software packages,        the possibilities for sending files over the Internet,        the machines that manufacture successive layers by using the received files directly,        as well as owing to the CARPYZ computer tool, which allows the rapid online creation of new products with very complex helical shapes and makes it possible to have them generated and manufactured by sending files anywhere in the world, bringing them from virtual to concrete almost instantaneously.        
Many Patents show the interest paid to machines for layer-based manufacturing: FR 2166526 (1973), U.S. Pat. No. 5,637,175 (1997), EP 1,358,994 (2003), WO2004/108398 (2004), etc.